Defense attorney Joe Amendola on Friday filed a 17-page response that says several of the alleged victims used drugs and alcohol as juveniles, which may have affected their memories.

Amendola wants a report by a psychologist related to the person described as Victim 6 in a grand jury report, because he believes it contains a conclusion that the boy wasn't sexually abused by Sandusky, a former Penn State assistant football coach.

Prosecutors didn't immediately respond to messages seeking comment. The sides are battling over what must be disclosed prior to Sandusky's trial on 52 counts.

The development comes as Penn State begins implementing recommendations offered by former FBI Director Louis Freeh, who is leading an internal investigation into the school's handling of the child sex abuse allegations against Sandusky.

Penn State President Rodney Erickson told university trustees at a meeting in Hershey on Friday that the university is enhancing background checks for staff working with children and adding more staffers to oversee its compliance with various federal laws and NCAA rules.

Erickson said Penn State will immediately retrieve keys, access cards and other property from people who aren't formally associated with the university. Sandusky, charged with sexually assaulting youths on campus, had a key to the football building long after his 1999 retirement.

Freeh's investigation is focusing on whether Penn State did enough to stop Sandusky from assaulting youths. The results of Freeh's investigation are expected later this year.

Erickson said a website that Penn State recently launched to foster greater transparency has garnered nearly 10,000 visitors and "seems to be facilitating a greater flow of information to our constituents."

Some ex-football players and vocal alumni disapprove of trustees' actions in the aftermath of the charges against Sandusky, including the ouster of the late Hall of Fame head coach Joe Paterno.

The trustees meeting began hours after Penn State's in-house lawyer said on the university website that "a number" of its employees had received subpoenas from the state attorney general's office. General counsel Cynthia Baldwin did not say how many were received, what information was sought or provide other details, and state prosecutors declined comment.

Spokesman Bill Mahon said the administration learned of the subpoenas after being informed by two employees who received the notice. Mahon said he had no additional information and referred questions to the state attorney general's office, which declined comment.